Do anatomic changes found in the throwing arm after a season of pitching resolve with off-season rest? A dynamic ultrasound study

HYPOTHESIS: Our hypothesis was that seasonal adaptive changes in the ulnar collateral ligament (UCL), ulnohumeral joint space (UHJS), and glenohumeral internal rotation deficit (GIRD) of the pitching extremity would subsequently resolve with off-season rest. METHODS: Eleven collegiate pitchers underwent preseason, postseason, and off-season evaluations including physical examination; dynamic ultrasound imaging of the UCL and UHJS; and the short version of the Disabilities of the Arm, Shoulder and Hand (QuickDASH) questionnaire. Ultrasound images were evaluated by 2 fellowship-trained musculoskeletal radiologists. RESULTS: All 11 pitchers were included in the final analysis, with an average age of 20.1 years and with 14.1 years of playing experience. After a season of pitching, we found significant increases in GIRD (P = .004) and UCL thickness (P = .033) and nonsignificant increases in both unloaded (P = .069) and loaded (P = .122) UHJS. Preseason GIRD correlated with this increase in loaded UHJS (r = 0.80, P = .003). The increase in UCL thickness was significantly greater in pitchers with GIRD greater than 10° (P < .05). After the off-season, UCL thickness returned to baseline and significant decreases were noted in both unloaded (P = .004) and loaded (P = .041) UHJS, but a progression in GIRD was found (P = .021). Pitchers with GIRD of 10° or less showed greater improvement in UHJS after the off-season (P < .05). CONCLUSIONS: The pitching season produced adaptive changes in the throwing elbow that subsequently resolved after off-season rest. However, shoulder range-of-motion deficits were progressive and did not resolve. Ultrasound adaptations of the pitching elbow were significantly related to GIRD.